The Distribution of Iron in Zsm-5 Type Iron Containing Zeolites and Ferrisilicates: Acidic and Catalytic Properties

Vorbeck, G.; Richter, M.; Fricke, R.; Parlitz, B.; Schreier, E.; Szulzewsky, K.; Zibrowius, Bodo

doi:10.1016/s0167-2991(08)62947-x

Cited by 19 publications

(8 citation statements)

References 12 publications

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“…A SUA1 = 52 ratio for this zeolite was estimated on the basis of adsorption calorimetric measurements, taking an amount of the adsorbed ammonia at 423 K as a measure of the SiOHAl lattice sites. 36 MFI ferrosilicate FeSil was prepared using iron sulfate and silicate solution as described in detail in ref 37. A SilFe = 32 ratio was determined by adsorption calorimetric measurements (see above).…”

Section: Methodsmentioning

confidence: 99%

(A,B,C) Triplet of Infrared OH Bands of Zeolitic H-Complexes

Pelmenschikov¹,

Wolput²,

Jänchen³

et al. 1995

J. Phys. Chem.

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Section: Methodsmentioning

confidence: 99%

(A,B,C) Triplet of Infrared OH Bands of Zeolitic H-Complexes

Pelmenschikov¹,

Wolput²,

Jänchen³

et al. 1995

J. Phys. Chem.

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“…[16], 57.6% of the original nonframework aluminium content of the ZSM-5 remained. The gallosilicate has about 41% of the gallium in form of nonframework species, whereas sample C3 has 39% of its iron in nonframework positions [17]. Probably, the nature and location of the nonframework species are different, but the overall amount is fairly comparable.…”

Section: Nature Of the Framework Elementsmentioning

confidence: 98%

“…Whereas the activity differences seem to correlate with the acid strength of the Brernsted sites related to A13+, Ga3+ and Fe3+ in framework positions, the different shape selectivity must have another origin. Of course, Ga3+ and Fe3 + have larger ion radii than A13+ and the resulting expansion of the unit cell volume is at least documented for iron [17,45], but this effect should be too small to modify the shape selectivity significantly, the more so, since only about one ion is incorporated into the unit cell (cf . Table 3).…”

Section: Nature Of the Framework Elementsmentioning

confidence: 99%

Isomerization of Meta‐Xylene Over Pentasil‐Type Microporous Gallosilicates

Richter¹,

Kosslick²,

Tuấn³

et al. 1992

Ber Bunsenges Phys Chem

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The isomerization of meta-xylene under normal pressure was studied in the temperature range 570-770 K on three catalyst series, oiz. (i) gallosilicates with a constant Si/Ga ratio of 50, but different synthesis times ranging from 5 to 96 h, (ii) gallosilicates with a higher (100) and lower (25) Si/Ga ratio after 48 h and 96 h crystallization time, and (iii) a series that included a ZSM-5 zeolite, a gallosilicate, and a ferrisilicate, all with comparable concentrations of Brernsted acid sites. The characterization of the catalysts is based on XRD, electron microscopy (TEM, SEM), ammonia thermodesorption, thermoanalysis and n-hexane adsorption. Synthesis products that were characterized by X-ray diffraction to have 100% crystallinity, aquire further acidity when the synthesis time is prolonged. This effect is due to an additional insertion of galtium in framework positions from a reservoir of nonfrarnework gallium species. -The isomerization on gallosilicates proceeds with negligible disproportionation to toluene. The activity is intermediate, compared to the ZSM-5 zeolite and to the ferrisilicate. The shape selectivity of the gallosilicates is inversely related to the crystallinity. -The kinetics of the isomerization can be described by a parallel two step model, in good agreement with experimental results. The significance of internal mass transport effects is discussed.Sample C2 is identical with sample A6. Sample B3 is identical with sample A6.' ' Sample B4 is identical with sample A7. Ber. Bunsetiyes. Phys. Chem. 96 ( I 992) No. 4 Ber. Burisunyr.~. Phys. Chnri. 96 / 1992) No. 4 I'CH Vr~ltrys~/esr//schrI/i mhH, W-6940 Weiriheim. lYY2 0005-902ljU2J0404-O~Y7 $ 3.50-k .25jO

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“…Microcalorimetric measurements of ammonia on these types of zeolites (FAU [27], MOR [28], MFI [22]) could suggest some -The change of the 1H MAS NMR chemical shift of a signal ascribed to the bridged hydroxyl groups in a zeolite upon adsorption of a weak base depends on the Si/A1 ratio of the zeolite skeleton. The Si/A1 ratios of ZSM-5, MOR(10) and HY (18) are above the value where no A1 is in the second coordination sphere of the Si-OH-A1 group. There the highest acid strengths can be expected, based on the NMR results.…”

Section: In Table 1 Are Summarized the Results Of The Ftir Measuremenmentioning

confidence: 80%

“…The preparation and characterization of the MFI type samples and of the FAU zeolites are described in ref. [18] and ref. [19], respectively.…”

Section: Methodsmentioning

confidence: 86%

FTIR spectroscopic and1 H MAS NMR studies of the influence of lattice chemistry and structure on Brønsted acidity in zeolites

et al. 1996

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The Distribution of Iron in Zsm-5 Type Iron Containing Zeolites and Ferrisilicates: Acidic and Catalytic Properties

Cited by 19 publications

References 12 publications

(A,B,C) Triplet of Infrared OH Bands of Zeolitic H-Complexes

(A,B,C) Triplet of Infrared OH Bands of Zeolitic H-Complexes

Isomerization of Meta‐Xylene Over Pentasil‐Type Microporous Gallosilicates

FTIR spectroscopic and1 H MAS NMR studies of the influence of lattice chemistry and structure on Brønsted acidity in zeolites

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